Fixed condenser



Sept. 1Q, N229, S. J. Wcog@ ET AL f 1mm@ commas@ Filed Dee., 25 i925INVN TORS 57%1/@2/ J Woon' Harry A. @regna J/t Y mw TH El E? ATTOF? NEYPatented Sept. 10, 1929.

UNITED STATES PATENT OFFICE.

STANFORD J. WOOD AND HARRY A. GREENE, JR., OF LOS ANGELES, CALIFORNIA.

FIXED CONDENSER.

Application filed December 23, 1925. Serial No. 77,264.

This invention relates to electrical condensers, and more particularlyto condenserS that are adapted to bc used in connection lwith highfrequency currents, such as in radio apparatus.

In such condensers, it has been common to use a series of interleavingplates, alternate plates connecting to a common terminal, and all ot'theplates being separated by a thin sheet ot dielectric material, suchas mica. This type of condenser is now quite common, and it is one ofthe objects ot' our invention to improve in general this kind ofapparatus.

It is another object of our invention to make it possible to reduce thecost of manufacture of such condensers` as well as the time necessary toassemble them. It is common, in this regard, to use dies for stampingsheet metal forming some ot the con` denser plates, and the cost ofmanufacture is reduced, by the aid of this invention, by so designingthe plates that fewer and less expensive dies are needed.

It is still another object ot' our invention to make it possible. duringthe process of manufacture, to set the value of the capacity of eachcondenser in a simple manner.

Our invention possesses many other ad- 'vant'ages, and has other objectswhich may be made more easily apparent from a consideration of oneembodiment ot our invention. For this purpose we have shown a form inthe drawings accompanying and forming part of the present specification.We shall now proceed to describe this form in detail. which illustratesthe general principles of our invention; but it is to be understood thatthis detailed description is not to be taken in a limiting sense, sincethe scope of our invention is best defined by the appended claims.

, Referring to the drawings:

Figure 1 is a side elevation of a stamping used as an end plate in ourcondenser;

Fig. 2 is an enlarged perspective view, illustrating the manner in whichthe end plates cooperate, but omitting all other parts for the sake ofclearness;

Fig. 3 is -a plan view of a complete condenser embodying our invention;and

Fig. 4 is an enlarged section of the condenser taken along plane 4 4 ofFig. 3.

The condenser is made of a plurality of plates forming a pair ofelectrodes, which are separated by a thin layer of dielectric. Eachelectrode may consist of one or more plates; in the present instance twoplates per electrode are shown. The end plates 11 form an importantfeature of our invention, since they are so arranged that duplicateparts can be used for both end plates, and that the process of centeringthe plates as'well as the insulation between them is 65 greatlyfacilitated. Each end plate has a central aperture 12, and has anaperturcd ear or terminal extension 13, extending from one side of thesubstantially rectangular body of the plate. rIhis extension servesconveniently as a means for making electrical connections to thecondenser, as will be rendered clear hereinafter.

At the side opposite from that of the ear 13, the plate has anintegrally formed eXtension or flange 14, extending at right angles tothe plate, and having a portion 15 that projects for a substantialdistance above the surface oi the plate 11. In this way, the portions 14and 15, serve as stops or guides 80 on each side of the plate.Furthermore, the bent-up portion 15 joins the body of plate 11 withsmooth curves, which provide beneficial electrical eiects as will becomeevident hereinafter.

Complementary to the parts 14 and 15, there are, on the opposite side ofplate 11,

a pair of similarly bent portions 16, one On each side of the ear 13.

The two en d plates 11 when assembled, are 90 placed in the relationshown most clearly in the diagram of F ig. 2. The portions 14 and 1G of:each plate serve to position the other.

`plate by extending over, but not touching those sides of the said otherplate which have no bent-up portions. Due to this arrangement, theconnecting ears 13 fall at right angles to each other.

The assembly of a complete condenser with these end plates 11 is shownmost clearly 100 it is to be noted that the surfaces of the conin Fig.4. First oi' all, a plate 11 is placed over a block of insulation 17,which is of a size ust sufiicient to tit between the rounded projectionsl5 and 1G, whereby this insulation is properly centered. On the otherside of plate 11, between the side extensions 14 and 16, there is firstdisposed a thin sheet 18 of mica or the like, which is square in formand lits fairly closely between the pro jections 14 and 1G of both endplates and is conlined thereby in central position.

The top end plate 11 may be placed directly over the sheet. 18, it atwoplate condenser is desired, in the manner shown in Fig. 2, and a bolton screw 19 can be passed through all ot the parts to hold themtogether. Ot' course, the apertures through all of the nietallic partsare made with a large clearance in order to prevent this screw fromshort-circuiting the plates.

However, in the present instance, a few intermediate plates are shown.Thus on top of sheet 18, there is indicated a thin inetallic plate 2Owhich has an ear similar to ear 13 extending in the direction of the earon the top end plate 11, and arranged to be electrically connectedtherewith. Then another sheet 21 of insulation can be used, over which athin plate 22 ot" metal placed, having an ear 23 placed over ear 13, andforining with bottoni end plate 11, one ot the condenser electrodes. Afurther sheet 24 of insulation separates this plate 22 from the top endplate 11, over which an insulation plate 25, similar to bottoni plate17, is placed.

It is evident that the condenser plates, and the dielectric sheets, canall be very readily assembled. The insulation strips 17 and 25 are .madeto iit accurately between the depending projections 14 and lo, toi-mingthe reverse bends, as clearly shown in the case of the top insulationstrip 25. `Furthern'iore,

ducting end plates l'l. are placed a considerable distance from theedges of the intermediate plates, and this is due in some measure to theprovision ot the upwardly extending humps or rounded projections 15. lnthis way, the undesirable edge etlect. is to seine extent remedied;there is no intense or irregularly large electrostatic tield adjacentthe edges.

We prefer to forni each end plate slightly arched, as indicated in Fig.1, in preference to a perfectly llat surface, so that by tighteningscrew 19, it is possible to flatten the plate only partly, and therebyto set the ultimate value ot the capacity of the condenser at preciselythat desired.

The condenser as thus described is simple to manufacture and toassemble; all olf the parts can be superposed, and then the screw 19passed therethrough without fue their adjustment.

l/Ve claim:

1. In an electrical condenser, a pair of end plates or substantiallyrectangular configuration, cach of said plates having at opposite sidesintegrally formed extensions projecting substantially at right angles tothe main portion ot the plate, a dielectric plate between the endplates. the extensions from each plate extending across the dielectricplate so as to define a rectangular space in which the dielectric plateis located, said extensions being suliiciently long to extend beyond theedge of the opposite end plate, and a pair of insulation plates, oneadjacent each of the outer surfaces of the end plates, said insulationplates being accommodated between the projectingextensions.

2. In an electrical condenser, a pair of end plates of substantiallyrectangular coniiguration, having at opposite sides, integrally formedextensions, and a series of alternate dielectric and conducting plateslocated in the space formed by t-he end plates and the extensions thatproject across the series, the edges oil the conducting` plates beingspaced from the extensions, and each of said extensions being connectedwith the main portion ot the end plate by a reverse bend, whereby asubstantial clearance is obtained between the edge of the conductingplates and the place where the extension nieets the inain portion of theend plate.

3. lln an electrical condenser, a pair of end plates, each of saidplates having, at a pair of opposite edges, extensions projectingsubstantially at right angles to the main portion ot the plate, wherebyguides are formed on each of the plates for those edges of the otherplate wlfich have no depending portions, a series et alternatedielectric and conducting plates located between the end plates, each ofthe extensions being connected with the main portion of the end platesby a reverse bend, whereby there is maintained a substantial clearancebetween the place where the extension meets the end plate, and theadjacent edges of the conducting plates in the series, a pair otinsulation strips, one adjacent each of the outside surfaces of the endplates, said strips also tting between the extensions, and means forfastening the end plates, the strips, and the series of plates together.

4. ln an electric condenser, a pair of end plates of substantiallyrectangular conguration, each of said plates having at opposite sidesintegrally formed extensions projecting substantially at right angles tothe main portion ot the plate and connected to the main portion of theplate by means of a reverse bend, a dielectric plate between the endplates, the extensions from each plate extending across the dielectricplate so as to de tine a rectangular space in which the dielectric plateis located, said extensions being sutli- Ciently long to extend beyondthe edge of the opposite plate, a pair of insulation plates, one

other by virtue of the projections and reverse adjacent each of theouter surfaces of the end bends, and a suitable clamping deviceprojectplates, said insulation plates being accommodated between theprojecting extensions and the reverse bends, and means for holding theentire assembly together.

5. In an electrical condenser, a pair of end plates of substantiallyrectangular configuration, each plate having atopposite sides,integrally formed extensions, and a series of alternate dielectric andconducting plates 1ocated in the space formed by the end plates and theextensions that project across the series, the edges of the conductingplates being spaced fromthe extensions, and each of said extensionsbeing connected with the main portion of the end plate by a reversebend, whereby a substantial clearance is obtained between the edge ofthe conducting plates and the place Where the extension meets the mainportion of the end plate, each plate having a centrally located opening,the openings in the insulating plates being of minimum size and theopenings in the conducting plates being larger, and a fastening deviceextending through all the plates thereby securely holding the assemblytogether.

6. A plate for an electrical condenser comprising a body having anopening at the center, a projection at one end serving as a terminal andmounting means, and lateral extensions projecting at substantially rightangles to the body of the plate and connected therewith by a reversebend, said bend forming, on either side of said projection, a shallowrecess, said plate also being slightly arched.

7. In a device o the class described, a radio fixed condenser,comprising a plurality of rectangularly shaped plates of electricallyconductive material, provided Wit-h an opening at their centers and aprojection at one end, a plurality of rectangles of dielectric materialinserted therebetween and superimposed thereon, said dielectricrectangles being longer than said plates, and being provided withopenings' in their centers of a smaller size than the openings in saidrectangularly shaped plates, clamping plat-es formed as rectangularlyshaped concave plates having )penings in their centers larger than theopenings in the dielectric rectangles, each of said clamping plateshaving a projection at one end serving as a terminal or mounting means,and longitudinal extensions projecting substantially at right angles tothe body of the plate and connected therewith by a reverse bend, saidbend forming a shallow recess on each side of the projection, saidclamping plates being placed on each end of the stack of dielectric andconductive plates; a pair of rectangular insulating plates provided withopenings at their centers and placed on the clamping plates therebycentering and squaring the clamping plates with respect to each ingthrou h the openings of all the plates in the assein ly and holding theassembly together.

in Witness whereof We have hereunto set our hands.

STANFORD J. VVODs HARRY A. GREENE, JR.

